Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for 49920 — Crystal Falls, MI

ZIP code 49920 (Crystal Falls, Iron County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is June 6 and the first fall frost September 9.

Where ZIP 49920 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone4a−30 to −25 °F
Coldest night−34.4 to −31.7 °C
Last frostJun 6
First frostSep 9
2012 zone4a

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 4a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Crystal Falls, MI…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Crystal Falls, MI

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostJune 6median — 50% chance of a later frost
Safe for tender plantsJuly 7only 10% chance of frost after
First fall frostSeptember 9median — 10% chance by Aug 20
Growing season94 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 24 and returns around September 25.

From the NOAA station Amasa 1w, MI — 10 miles away, elevation 1,470 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 49920

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 25 – May 9
SpinachSow outdoors · Apr 25 – May 16
Broccoli, cabbageStart indoors · Mar 28 – Apr 11
Broccoli, cabbageTransplant · May 16 – May 30
Onion setsPlant outdoors · May 9 – May 23
PotatoesPlant outdoors · May 16 – May 30
LettuceSow outdoors · May 9 – May 23
Carrots, beetsSow outdoors · May 16 – May 30
TomatoesStart indoors · Apr 11 – Apr 25
TomatoesTransplant · Jun 13 – Jun 27
Peppers, eggplantStart indoors · Mar 28 – Apr 11
Peppers, eggplantTransplant · Jun 20 – Jul 4
BeansSow outdoors · Jun 13 – Jun 27
Sweet cornSow outdoors · Jun 13 – Jun 27
Cucumbers, squashSow outdoors · Jun 13 – Jun 27
Fall lettuce, spinachSow outdoors · Jul 15 – Jul 29
GarlicPlant cloves · Aug 26 – Sep 30
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 6) and first fall frost (Sep 9) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 49920 came on Apr 27 — about the same time as the 1991–2020 average (Apr 28).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 4a in Michigan

443 plants native to the lower 48 states, recorded in Michigan, and rated by the USDA to survive −30 °F or colder — the bottom of zone 4a. Each links to its USDA PLANTS profile.

Trees 48

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 78

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °F

Wildflowers & perennials 168

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °F

Grasses 136

alpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbeaked sedge4 ft · blooms late spring · low shade tolerance · to −38 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °FBicknell's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 4

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Ftrumpet honeysuckle16 ft · blooms late summer · low shade tolerance · to −33 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Crystal Falls, MI.

Soil in Crystal Falls, MI

The soil mapped at the center of ZIP 49920 is Minocqua — muck, poorly drained.

TextureMucktop layer
pH4.5strongly acidic; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter75%high
Hydrologic groupB/Dmoderate when drained; wet otherwise
Farmland classPrime farmland if drainedUSDA classification

Map unit: Minocqua-Channing complex, 0 to 3 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 49920; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Crystal Falls, MI

Summer high79 °Faverage high, July
Winter low0 °Faverage low, January
Hot days4days a year at 90 °F or more
Freezing nights203nights a year at 32 °F or less
Growing degree days1,526base 50 °F — the season’s usable heat
Longest day15 h 46 mindaylight on June 21
Shortest day8 h 37 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation31.4 inper year, rain and melted snow

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 22 °F, low 0 °F 22°0° JanFebruary: average high 26 °F, low 0 °F 26°0° FebMarch: average high 37 °F, low 10 °F 37°10° MarApril: average high 50 °F, low 24 °F 50°24° AprMay: average high 65 °F, low 37 °F 65°37° MayJune: average high 74 °F, low 46 °F 74°46° JunJuly: average high 79 °F, low 51 °F 79°51° JulAugust: average high 76 °F, low 49 °F 76°49° AugSeptember: average high 68 °F, low 42 °F 68°42° SepOctober: average high 54 °F, low 31 °F 54°31° OctNovember: average high 39 °F, low 21 °F 39°21° NovDecember: average high 27 °F, low 8 °F 27°8° Dec

Precipitation by month inches

0″1″2″3″4″January: 1.32 in precipitation 1.3 JanFebruary: 1.11 in precipitation 1.1 FebMarch: 1.73 in precipitation 1.7 MarApril: 2.78 in precipitation 2.8 AprMay: 3.07 in precipitation 3.1 MayJune: 3.57 in precipitation 3.6 JunJuly: 3.89 in precipitation 3.9 JulAugust: 3.20 in precipitation 3.2 AugSeptember: 3.63 in precipitation 3.6 SepOctober: 3.27 in precipitation 3.3 OctNovember: 2.14 in precipitation 2.1 NovDecember: 1.64 in precipitation 1.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Amasa 1w, MI (10 mi away); precipitation: Amasa 1w, MI (10 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

3 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

499024b
Alpha, MI · 7 mi
498814b
Sagola, MI · 13 mi
499274a
Gaastra, MI · 14 mi
499644a
Stambaugh, MI · 16 mi
499034a
Amasa, MI · 16 mi
499154a
Caspian, MI · 16 mi
498794a
Republic, MI · 18 mi
541214b
Florence, WI · 19 mi

Michigan planting zones →

Questions about 49920

What planting zone is ZIP code 49920?

ZIP code 49920 (Crystal Falls, MI) is in USDA hardiness zone 4a on the 2023 map: the coldest night of an average winter reaches −30 to −25 °F (−34.4 to −31.7 °C).

When is the last frost in Crystal Falls, MI?

The median last spring frost (32 °F) near 49920 is June 6; after July 7 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Amasa 1w station.

When is the first frost in Crystal Falls, MI?

The median first fall frost near 49920 is September 9, giving a median frost-free growing season of 94 days.

When should I plant tomatoes in 49920?

Start tomato seeds indoors around Apr 11 – Apr 25 and set transplants outside around Jun 13 – Jun 27, one to three weeks after the median last frost.

How much rain and snow does 49920 get?

About 31.4 inches of precipitation a year (NOAA 1991–2020 normals, Amasa 1w station).

How hot do summers get in Crystal Falls, MI?

The average high peaks at 79 °F in July, with about 4 days a year at 90 °F or more.

What kind of soil does 49920 have?

The USDA soil survey maps Minocqua at the center of ZIP 49920: muck, poorly drained, pH about 4.5 (strongly acidic).

Did spring come early in Crystal Falls, MI in 2026?

Spring leaf-out near 49920 came on Apr 27 in 2026, about the same as the 1991–2020 average (Apr 28), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Crystal Falls, MI?

Long-day onions: the longest day near 49920 is 15 h 46 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).